LEGO Interface A (9750/9771) – LEGO Technic Control 1 (TC1) reference/ideas thread

[Toastie]

3 hours ago, Gunners TekZone said:

So... something is not playing nicely with something else on the cards.

Merde.

OK, just quickly: You do "initialize" the card (which is just poking the direction register of the 6522 VIA), correct?

Otherwise, it does not really know what to do other than factory settings upon power up.

Best
Thorsten

  

[Gunners TekZone]

11 minutes ago, Toastie said:

You do "initialize" the card

I suspect LEGO TC Logo does that (and I did set it for the correct slot I am using #2), as it will control four of the ports (2, 3, 4 , 5) if I use their "opposite" numbers. Eg: #5 for port 2.

Same results with BASIC.  I can POKE the values 4, 8, 16, 32 to toggle port 5, 4, 3, 2 respectively.

Edited Wednesday at 08:40 AM by Gunners TekZone

[Toastie]

I see - yes, TC Logo should do that.

Hmm - sounds like a hardware issue then ... the different VIAs you puchased are all behaving in the same way, right?

Best
Thorsten

[Gunners TekZone]

Yes, both are SY6522A from the larger of those two IO cards I had.  But I also swapped in a MOS-6522 from a VIC-20 and it is the same.  So either these older VIAs dont work quite the way the "newer" support ICs (and possibly the schematic wiring) are expecting?? 

I can find a W65C22N6TPG-14 on Mouser (seems to be the closest "newer" VIA to the one listed on the schematic)... But at about $50 CAD, I am not planning on getting one, on just a wim.

Edited Wednesday at 08:57 AM by Gunners TekZone

[Gunners TekZone]

Hmm... looking at it I was starting to see the pattern... 

What the interface should be seeing:

 IN          OUT

7 6     5 4 3 2 1

What it seems to be seeing:  with the Inputs always TRUE and Ports 1 & 2 always HIGH
 IN          OUT

1 2     3 4 5 6 7

Somehow the card is sending inverted bits to the interface!!   But so far I can't see how... I have been tracing the lines and ribbon cable and everything seems correct, granted all I have is the schematic this PCB is modeled on.  

Edited Wednesday at 09:20 AM by Gunners TekZone

[Toastie]

Ribbon cable original LEGO (I know, it sounds like: Did you plug it in ... sorry for that)?

I once managed to screw up when crimping the connector on ... 

Best
Thorsten

[Gunners TekZone]

I used the original cable (70412) that came with my newest Interface-A (not the one pictured, as I was swapping them around to test), and had considered that it was flipped or backwards... But by its design that would have probably put all grounds to the data pins, and put the 5v and GND on totally wrong pins.

However, I was right in  my observation... Somehow this PCB is reversing JUST the 8 data lines.  I took some dupont wires for 5V & GND and Ports 0-7, but I reverse the port wires on the interface (Pin 6 on the PCB to Pin 20 on the Int-A... Pin 20 on the PCB to Pin 6 on the Int-A... and so on).

Works as it should now!!  Go fig!?!  Now I can either mod a specific cable for Apple use only...  Or (more likely) cut 8 traces and bodge 8 wires on the PCB to reverse the 6522 PBx lines to the appropriate ribbon cable connector pins.

What a bother    But now I know I can successfully run an Interface-A (or two) on my APCO Apple IIe clone 

 

Edited Wednesday at 10:21 AM by Gunners TekZone

[alexGS]

6 hours ago, Gunners TekZone said:

, I am testing with LEGO TS LOGO and oddly, they both have the same issue:  Ports 0 & 1 are always ON, which is no good.  And ports 2, 3, 4 ,5 work as expected, but are referenced backwards as 5, 4, 3, 2.    And it seems both inputs register as TRUE, all the time, although they indicate properly on the Interface.  Well mostly... there is odd interactions when using both, but only when plugged into the card.

Is it possible the footprint for the 20-pin ribbon connector was reversed? Just thinking of how the 5, 4, 3, 2 occurs with 1 and 0 perhaps treated as the inputs

[Gunners TekZone]

Earlier I had tested with LEGO original and standard ribbon cables.

But as you should be able to see in 2nd photo, it is only the 8 data wires that needed to be flipped along the long axis to "fix" it, so issue resides on the PCB, somehow.

One would have to compare the traces with an original card to confirm.

 

Edited Wednesday at 11:13 AM by Gunners TekZone

[Toastie]

Could it be that there were different cables for the Apples and for the IBMs? Or do these cables have the same product ID?

Best
Thorsten

 

[evank]

4 hours ago, Gunners TekZone said:

Earlier I had tested with LEGO original and standard ribbon cables.

But as you should be able to see in 2nd photo, it is only the 8 data wires that needed to be flipped along the long axis to "fix" it, so issue resides on the PCB, somehow.

One would have to compare the traces with an original card to confirm.

 

I think that's correct. A few years ago, a Chinese ebay seller was offering those cards. I bought one and it didn't work. My friend Scott bought one too and reached the same determination as you: the data pins are wrong. He made a twisted cable and sent it to me. Now it works fine.

The best aftermarket 9767 card is Blocko. Anybody who wants an original Lego card should ask me; I've got some to spare.

[WhitneyDesignLabs]

I've used the Chinese clone boards before. I definitely had to to the "cut & twist" method on the ribbon cable. Can confirm. But after doing that, clone worked fine. I have never had an authentic board, just the authentic Interface A mated to the Chinese clone.

Scott

whitneydesignlabs

[Toastie]

5 minutes ago, WhitneyDesignLabs said:

I definitely had to to the "cut & twist" method on the ribbon cable.

Well, that issue was solved quickly! I love this place

And welcome to EB, Scott!

All the best
Thorsten

[Gunners TekZone]

4 hours ago, evank said:

A few years ago, a Chinese ebay seller was offering those cards.

What cards???   This was just made by PCBWay based directly on a design by David M back in 2019 and posted on the Applefritter forum.  Perhaps he followed the tracing of such?  If so I find it odd no one else used, noticed and commented about this issue (in his layout) since. But then it is a niche but loyal market   I have messaged him already about issue and fix.

Oh well... Now I know and the fix (for mine at least) is a simple bodge, no need to mod a cable that must follow those cards around forever..
 

4 hours ago, evank said:

The best aftermarket 9767 card is Blocko. Anybody who wants an original Lego card should ask me; I've got some to spare.

Unfortunately, all too ridiculously pricey for what they are. 

I am in about $60 CAD for two, and three more boards that I might source out VIAs for... In case I want to follow in your footsteps and use ALL the interface-A's  

However, I think you are the king there 

Edited Wednesday at 07:49 PM by Gunners TekZone

[evank]

They're long gone, but a Chinese seller was selling the DM's Reboot. I have no idea if DM allowed this or if the cards were just crappy knock-offs. I'm not going to ask DM himself, because I just don't like him personally.

I think the Blocko price is fair.

"It's good to be the king." - Mel Brooks

[Gunners TekZone]

47 minutes ago, evank said:

but a Chinese seller was selling the DM's Reboot.

Ah, yes... that would make more sense.

 

47 minutes ago, evank said:

I think the Blocko price is fair.

Perhaps "fair" in the sense of a niche product for a slim audience... But in no way for what it is component and (lack of) complexity wise.  These Apple and IBM Interface cards are very simplistic in that sense.

 

1 hour ago, WhitneyDesignLabs said:

I definitely had to to the "cut & twist" method on the ribbon cable. Can confirm. But after doing that, clone worked fine. I have never had an authentic board, just the authentic Interface A mated to the Chinese clone.

Welcome!!  Join the club... Well, I guess I am the one joining the "clone" club. 

- APCO Apple IIe clone that needed minor trace repairs.

- A "bodged to work" LEGO 9767 (reboot) card.

 - And (initially) a VIC-REL (reboot) Interface-A like board (minus the built in H-Bridges) - Pictured below, with my experimenter breadboard addon. 

But all together, I still purchased all three for less than a Blocko!

I seem to be all about the Prep-to-Play over Pay-to-Play experience 

 

And yes... The VIC-REL on my VIC-20 is "relevant" as I am using it to try my hand at designing a simple routine programmable program for the Interface-A on the VIC-20.  Perhaps a LEGO Lines type port in time??  But that might be outside my coding skills.

 

Edited Wednesday at 08:42 PM by Gunners TekZone

[Gunners TekZone]

The "irony"...   In my attempt to avoid point to point soldering, I opted for the Reboot PCB option.  And ended up doing exactly that anyhow to fix this boards' "issue".  I can run, but I can't hide.

Turns out even that repair was super simple... Although I continue to give GOD the glory  for clearing the brain fog  and for the insight, as was required to get this far.

Here is a nice closeup for anyone wanting to do the same, but don't forget to cut the equivalent traces along that top row of the VIA (on both sides of PCB).

 

Now I too have multi-brand computer options for my two Interface-A boards   I'll fix the 2nd card as well... For when I breakdown and get a 3rd Int-A.. which apparently must happen, as I still have empty slots in the APCO  

 

Edited Thursday at 03:32 AM by Gunners TekZone

[evank]

My mistake: I'd forgotten that our hero @alexGS had discovered the Reboot card mistake a couple of years ago.

Edited Thursday at 01:35 PM by evank

[alexGS]

Thanks Evan - I was slow off the mark on this thread (sorry, Gunners) - I thought the symptoms sounded familiar. I think it’s a board layout mistake from putting the header footprint on the wrong side.

I have a photo of my solution, but can’t upload it here as there’s a size limit for me of 15.78KB. I used a panel-mount 20-pin header (screwed to the back of my Apple IIGS) and, counting from red (pin 1), split the ribbon between wires 5 and 6, and turned over the remaining strip of wires 6-20 before crimping into the 20-pin plug that goes into the 9767 Reboot board. To clarify, the red wire is still pin 1, so the first five wires are not twisted. I didn’t change anything on the board itself.

Crimping ribbon cable connectors is best done with a bench vice - the jaws stay parallel - or a Vise-Grip welding clamp can be used (the jaws have wide plates)

A standard ribbon cable to the Interface A then plugs into the 20-pin header without having to open the computer for setup/packdown. It’s the same type of bolted-on header that older Apple IIs used for the floppy drives.

I really should have documented this by making a PDF, just never got around to it. Again, sorry about that

 

Edited Thursday at 12:41 PM by alexGS

[Gunners TekZone]

9 hours ago, alexGS said:

(sorry, Gunners) - I thought the symptoms sounded familiar. I think it’s a board layout mistake from putting the header footprint on the wrong side.

No apologies required.  Solving (or re-solving) issues is a great way to learn, and I am finding it more beneficial to my clarity of thought then I would have suspected. 

The PCB was simply laid out wrong in this one area of the header, as every other pin is correct in all orientations.  Here is my "corrected" version of the "problematic" schematic that I think the Reboot PCB was modeled after... I hope I got it right    Unfortunately, I am not well-versed (or even poorly -versed) in the art of CAD/PCB design and layout, so I can't make a corrected PCB (maybe one day... Look out $$$ Blocky).



Meanwhile, now I have two cards active, one for the "Apple IIe's" Interface-A and the other to mess around with alternate interface programming.  Here I have the 2nd one with all 8 ports set to output (using 3mm LEDs with built-in resistors, just jammed into the ribbon cable for expediency  )  So as to display the 8-bit binary output of an input number.  Super simple stuff, but great to confirm code and pin orientation. 

And makes a good Larson Scanner 

I also realised there is nothing preventing these two cards from controlling a totally customised LEGO interface with any combination of inputs and outputs.  It is just opto-isolators and H-bridges.  Requiring custom code of course.  But think about it, one 16 port 4.5v compatible (or even 12v for trains!!) LEGOlike Interface-DIY (Patent Pending  ) perhaps with 6 inputs and running 5 motors, etc... Options!

Edited Thursday at 09:48 PM by Gunners TekZone

[Toastie]

45 minutes ago, Gunners TekZone said:

It is just opto-isolators and H-bridges.

Yeah - and that is what Interface B is as well, however, >providing< the 8 input data constantly, where outputs are again H bridges.

Now just out of curiosity: If you had soldered the header to the other side of the PCB, would have done the trick? Provided it is even "solderable" on that surface? Or are there further issues, when (theoretically) doing that?

Best
Thorsten

[Gunners TekZone]

1 hour ago, Toastie said:

Now just out of curiosity: If you had soldered the header to the other side of the PCB, would have done the trick?

No.  But the proof of such is in the 'pudding' (AKA my 8 pin inverted swap worked  )

Again, it was ONLY the eight pins 6, 8, 10, 12, 14, 18 & 20. on that connector that were "wired" as incorrectly inverted, TOP to BOTTOM in relation to the 6522's PB0-PB8. 

Flipping the whole connector Horz or Vert would NOT have fixed anything, but also messed up the 5v pin positions.

Consider that on the "faulty" schematic, the order of a single pin from the Apple slot, through the 74LS245 to the 6522, and then to the ribbon connector is a set of flip-flopping (HIGH/LOW) pin designation inversions... Probably to keep IC placement and trace runs clean.

The address for the Int-A Output Port 0: D1(Apple) to B7/A7 (74LS245) to D0/PB0 (6522) to Pin 20 (Input 7 on Ribbon connector).  (the Red/Green colours represent the Input/Output Int-A LEDs) This last step shouldn't have been inverted, but the author might have just gone with the flip-flop flow. 

The correct last step is D0/PB0 (6522) to Pin 6 (Output 0 on Ribbon connector)... And so on for the remaining pins.

I didn't realise it at the time (groggy eyes get crossed  ) but there is another schematic, that is also on Evans website, that shows this correct layout. 

And hey, if someone posts a PCB layout back in 2019 and NO ONE seemed to notice and/or make a clear indication of it being in error (at least not on the forum I found it on)... Then how was I to know?  This is me trying to make that PSA for others   

 

Edited Thursday at 11:52 PM by Gunners TekZone